1. Field of the Invention
The present invention relates to a spring rail frog or rail intersection used in railroad track equipment. The spring rail frog assists in transferring the wheels of the train from one track to another track.
2. Description of the Related Art
When a train is to be diverted from one track to another, a turnout is installed, which is essentially a curve connecting two parallel or diverging tracks. This curve, however, is composed of three principal parts: (1) a switch, consisting of two movable rails to direct the train onto one track or the other, as desired;
(2) a frog to allow the wheel flanges to pass the intersection of the rails; and (3) rails, known as lead rails, connecting the frog with the switch rails. The frog is the part where the curved rail for the diverging line crosses the straight rail for the straight ahead move.
There are many different types of frogs including rigid frogs with no moving parts and movable wing frogs that have one or two of the wing rails that can move outwardly to provide a flangeway for the wheel flange. Movable wing frogs also have different types of frogs. The spring rail frog is a movable wing frog where one of the wing rails moves to provide the flangeway.
When two running rails intersect, a spring rail frog allows the wheel flanges to transfer from one rail to another rail.
Spring rail frogs have been known for a very long time. The Weir Frog Company catalog from 1898-9 details many different types of spring rail frogs.
U.S. Pat. No. 2,036,198 discloses a spring rail frog that includes the usual frog point and fixed wing rail secured to the branch line rail and a spring pressed wing rail secured to the main line rail. The spring pressed wing rail is normally held against the frog point to provide a continuous supporting surface for the treads of the wheels running along the main line. This spring rail frog allows the wheels of the branch line trains to automatically open the flangeway between the spring pressed wing rail and the frog point. A dash pot arrangement is provided for automatically controlling the lateral movement of the spring wing rail to prevent its rapid return from an open to a closed position between successive sets of wheels on a train. This invention is directed at eliminating the undesirable action commonly known as slapping back. However, there is no provision in this reference for accomplishing a smoother transfer of each wheel by shortening the bending region of the spring rail or changing the height of the spring rail relative to the nose rail.
U.S. Pat. No. 4,624,428 discloses another type of spring rail frog. This frog includes a spring wing rail having a first position where its free end contacts the long point rail and a second position where the free end is spaced from the long point rail to provide a flangeway therebetween. The spring wing rail is rigidly fixed at a point intermediate the free end and a closure rail engaging end so as to move to allow the spring wing rail to move to the second position when it is stressed by a lateral force applied to it by the flange of a rail car wheel traversing the flangeway. As the spring wing rail is moved to the second position by this force, the spring wing rail is bent along a significant length of the rail in a cantilevered fashion. This bending zone extends from approximately the spacer block to the nose rail.
While these two patents disclose techniques for transferring train wheels from one rail to another using spring rail frogs, there is still a need to improve the smoothness of the transfer of the train wheels. In part this desire for improved smoothness in transfer is because the bending zone of these references is quite large and allows a significant gap to be generated between the spring wing rail and the nose rail. This in turn results in the wheels running on the crossing area for a longer time thereby decreasing the smoothness of transfer.
Also, these references do not allow any adjustment in the height of the spring wing rail relative to the nose rail so as to improve the smoothness of the transfer of wheels on the rails.